Bearings are commonly used whenever two contacting parts rotate with respect to one another, such as in automatic transmissions and planetary gear sets. During part assembly, handling individual rolling elements is cumbersome and time consuming. To combat these issues, rolling elements are installed into bearing cages to produce a lightweight, easy to manipulate assembly able to simplify rolling element installation and maintain equal rolling element spacing during part assembly and operation.
Once installed, normal operation of a planetary gear set causes a bearing assembly to rotate simultaneously with respect to the planetary gear axis and the carrier gear axis. Due to the mass of the bearing cage, the rotation results in large amounts of centripetal acceleration, and consequently, movement of the bearing cage radially outwardly to contact the inner surface of the bore in which it was received. As carrier speeds increase, the pressure of the outer surfaces of the cage contacting the inner surface of the respective bore similarly increases. Ultimately, the pressure forces, in addition to the added velocity, increase the PV (Pressure×Velocity) experienced by the bearing cage and may limit the bearing assembly's operating envelope.